Hair follows a specific hair cycle. A phase in which keratinocytes around hair dermal papilla divide and proliferate is referred to as “anagen”. Anagen is followed by catagen in which hair stops its growth and is separated from the hair papilla. Catagen is followed by telogen in which keratinocytes do not grow and hair is lost after a certain period of time. The hair cycle consists of anagen, catagen and telogen, which are repeated. The anagen phase in adults usually differs between individuals, but it is known that the anagen phase is 3-5 years for males and 4-6 years for females and that about 15% of hair is in the catagen and telogen phases. Human hairs follow independent hair cycles, and grow on one side but are lost on the other side so that the total number of hairs will be uniformly maintained. This hair loss is referred to as physiological hair loss. However, in addition to the telogen phase of the normal hair cycle, diseases, hair care products (gel, wax, etc.), stress and the like may cause hair loss, and in this case, when the cause is removed, the hair growth is restored again.
Baldness does not mean that hair does not grow again after hair loss. In the case of baldness, hair gradually become thinner and converts to vellus hair. As this phenomenon progresses, the hair papilla present in the hair root becomes smaller. When the hair papilla becomes smaller, the thickness of the hair also become thinner and, at the same time, the hair cycle becomes shorter, and newly grown hair becomes further thinner. As baldness continuously progresses, the hair converts to vellus hair, and the hair cycle becomes shorter so that the hair is lost faster than growth. In addition, unlike alopecia areata known to be caused by autoimmune disease, and temporal hair loss that is caused by endocrine disease, nutritional deficiency, drugs, or physical and mental stresses such as child birth, baldness tends to be inherited, and the degree of baldness is diverse. Furthermore, baldness is known to be associated with a blood male hormone (androgen).
Currently, it is known that, when Minoxidil that is a topical medication and Propecia (finasteroid component) that is an oral drug are used in the initial stage of hair loss, the progression of hair loss can be somewhat delayed. However, already progressed hair loss is difficult to restore to the normal state, and in this case, hair transplantation can be considered. In hair transplantation, about 1000-3000 hairs are collected by an incision method or (non-incision method) from side hairs above the ear portion and back hairs, which are less sensitive to hormones, and the collected hairs are transplanted. However, the number of hair transplantations is limited.
Currently commercially available products are known to have effects on the prevention of hair loss, but show insignificant effects on hair growth. In addition, when the use of these products is stopped, problems arise again. Furthermore, these products are disadvantageous in terms of costs.
In recent years, methods of treating hair loss using genes and methods of treating hair loss using stem cells have been developed. In prior art documents related to the background of the present invention, Korean Patent No. 10-0771171 (issued on Oct. 29, 2007) discloses a method comprising isolating and proliferating follicular stem cells and allowing the cells to differentiate into follicular cells, and a composition for treating baldness, and Korean Patent Laid-Open Publication No. 10-2008-0097593 (laid open on Nov. 6, 2008) discloses a cell therapy agent prepared by suitably mixing adipose-derived stem cells with follicular stem cells. In addition, Korean Patent No. 10-1218101 (issued on Jan. 3, 2013) discloses a composition for stimulating hair growth and preventing hair loss, which contains, as an active ingredient, a conditioned medium of amniotic fetal mesenchymal stem cells. However, a composition for stimulating hair growth or preventing hair loss, which contains a conditioned medium of neural stem cells or an extract of neural stem cells and has excellent effects, has not yet been reported.
Accordingly, the present inventors have characterized a conditioned medium of neural stem cells or an extract of neural stem cells by applying the conditioned medium or the extract to human dermal papilla cells (hDPCs), and have found the effects of the conditioned medium or the extract on the stimulation of hair growth or the prevention of hair loss by use of C57BL/6 mice in vivo, thereby completing the present invention.